Blog

We build amazing iPhone and iPad apps. We recently built ABC Play School Play Time and Art Maker for iPad, and recently wrote Learning Cocoa with Objective-C Fourth Edition and the iOS Game Development Cookbook for O'Reilly. This is our blog.

Some quick thoughts from Secret Lab on the mind-blowing collection of WWDC 2014 announcements from Apple.

OS X Yosemite

Pretty! Made simpler. Not super sold on translucency, though.

Handoffs and Continuity is awesome. Will be super useful. Devs get access to this too. Reminds us of the excellent “Send to Chrome” feature in Android. Only really polished.

iOS 8

Not a huge amount of new stuff, visuals wise; however, there are some awesome behind the scenes changes.

Custom Actions, Photo Editing, Sharing Options can all be provided by apps. You can make your app provide services to other apps. This is AWESOME - it’s going to make the app ecosystem quite a bit richer.

Android’s had this for some time, and it’s great to see it in iOS.

The ability to put widgets in the notification center is also great, lots of devs are going to make some great stuff with this.

Being able to share documents between apps without having to copy them is going to be Super Nifty. This has been a real weakness of iOS until now.

Swift

WOW. Apple developed an entire language, wrote all the docs, and wrote all the supporting tools for it, without it leaking. This is really impressive.Can’t wait to use this.

The language is very modern. Its syntax feels like a mashup of Python, Haskell and Ruby.

Interoperation with Obj-C is rather nicely handled. They’ve directly translated ObjC’s arguments-are-embedded-into-method names approach into named parameters. The goal was clearly to make it as painless as possible to work with both languages in a single project.

Something that’s interesting is it’s completely opposed to Objective-C’s way of doing things is that, while ObjC allows sending messages to nil (thereby making it safe to not have to do null checks), Swift instead guarantees that all values that are not Optionals are non-null. Optionals are a very cool feature: in other languages, the concept of “nothing” is usually represented by a special value (for example, Lua’s ‘nil’ value), or by convention (for example, in C, the value 0 means ‘nothing’). This creates its own problems; if you use a special value, comparing it to other objects means you have to do type conversions, and if you instead use the convention of zero meaning null, you have to do checks. Objective-C goes some of the way towards helping with this: it defines ‘nil’ as a special value that’s represented a zero pointer, but calling methods on it is safe because the runtime automatically returns if it notices you’re trying to call methods on nil.

This is nicer than crashing, but it can lead to problems, since if an object you’re trying to work with is unexpectedly nil, you’ll get bugs. Not crashing bugs, but weird behaviour bugs.

The Optionals system is nicer. In Swift, a value is either guaranteed to be a valid one, or else is explicitly known to sometimes be nil.

For example: if you’re converting strings to integers, your code looks like this:

lettheString="123"lettheInt=theString.toInt()

In most languages, the ‘toInt()’ method would return a value that represents ‘not valid’, such as 0. But in Swift, it returns an optional int - that is, a value that MIGHT represent nothing, but if it doesn’t represent nothing, then it’s GUARANTEED to be an integer and nothing else.

This makes things quite a bit safer, since the compiler’s able to do more checking, and is able to reason about your code better.

Swift is filled with this kind of thing. Another example: in C and similar langauges, the assignment operator (=) returns a value, like this:

a=b=3// sets both a and b to 3

In Swift, that doesn’t apply. This means that the following is actually a compiler error (it’s just a warning in ObjC):

ifx=y {
…
}

We’re not huge fans of the range operators: a...b means “range from a to b, including b” and a..b means “range from a to b, not including b”. Notice that they only differ by a single period. That’s going to lead to bugs, due to typos.

The mutability of variables depends on whether or not the variable is declared as a constant or not. This is nicer than Objective-C, which has two different classes for each type based on whether it’s mutable or not (ie NSString vs NSMutableString)

This only applies to strings, arrays, dictionaries, and other low-level things. We’re still going to be stuck with NSURL vs NSMutableURL for a while.

Playground is super cool. Reminds us of IPython, in that you can figure out your code without it having to be run inside a larger app. This is going to make development a lot faster.

App Store

Being able to show videos and make app bundles (with discount) is going to be neat. Not a huge game changer for us, but any increase in app store functionality is good.